FYI i end with 18FPS for full animated lovyanGFX on two displays.
Only urgent in lovyanGFX DMA use is accept, that call gfx.pushImageDMA setup window for LCD only if previous x,y,w,h differs and setup only diff.
Result to trouble between switching LCD1 LCD2.
Workaround is send one dummy pixel if chip select toggles, that forcing send new window instruction into right LCD over DMA transactions.